A separate Scotland would create a “less stable world” because it would be too
small to “contribute meaningfully” to global security, one of the US’s most
influential newspapers has concluded.

A Washington Post editorial warned Scottish independence would significantly weaken the UK, which it praised as America’s foremost ally.

Separation could destabilise the pound and cost the remainder of the UK its seat on the United Nations Security Council, the newspaper also argued.

However, it said the UK could retaliate by vetoing Scotland's entry to the European Union and laying claim to a third of the North Sea's oil fields.

The newspaper, which claims to have 26 million readers, said Scottish independence is part of a "worrying trend" towards European regional fragmentation, citing similar separatist movements in Spain and Italy.

Opposition parties said the editorial showed the concern that foreign allies have about separation but the SNP complained it contained factual errors.

However, it reflects concerns highlighted by the Foreign Office, which has warned hostile leaders abroad will exploit independence to try and curtail the UK’s power on the world stage.

In its editorial, the Washington Post said: “An independent Scotland would significantly weaken the foremost military and diplomatic ally of the United States, while creating another European mini-state unable to contribute meaningfully to global security.

“The more fragmented Europe becomes, the less it will be able to use its collective strength on the global stage, both in military and diplomatic terms.”

The newspaper said a separate Scotland would expel the UK’s Trident nuclear deterrent, keep an Army of up to 10,000 soldiers and withdraw from Nato.

Although the SNP recently narrowly voted to drop its opposition to the nuclear alliance, this is on the condition that a separate Scotland could expel Trident, a condition that experts claim would be unacceptable.

The Washington Post also warned the EU “might demand that Scotland commit to the wobbly euro.”

Jackson Carlaw, Scottish Tory deputy leader, said: “Here is a fairly definite and concise view of how others see a separate Scotland's role in the world. As it stands, we have a strong voice and an important role to play by virtue of being part of the UK on organisations like Nato and the UN.”

Willie Rennie, Scottish Liberal Democrat leader, said: “In the midst of a presidential election and the devastation of Hurricane Sandy for one of the United States’ leading newspapers to write such an article reveals the anxiety that exists about Scottish independence across the Atlantic.”

The SNP said it had written to the newspaper pointing out “factual errors” in the editorial but only highlighted one, the new policy on Nato.

“We look forward to an independent Scotland being a friend and ally of the United States, as we will be with the rest of the UK,” a spokesman said.

Meanwhile, the country’s tourism chief said the 2014 Homecoming celebration of Scottish culture will succeed despite the cancellation of a controversial clan meeting.

But Mike Cantlay, chairman of VisitScotland, confirmed that a repeat of 2009’s The Gathering will not be staged after Stirling Council decided the £700,000 cost was too high.